The item ID for Flagstone Wedge Steep Corner Top is flagstoneWedgeCNRSteepTop
This is the GiveSelf spawn command to give yourself Flagstone Wedge Steep Corner Top in 7 Days to Die.
Copy the command below and paste it into your 7 Days to Die game or server admin console to obtain. You can open the console by pressing usually one of these keys (F1, F2, *).